The goal of this K23 Mentored Patient-Oriented Research Career Development Award is to support the applicant in developing the critical skills necessary for an independent research program around the implementation of evidence-based treatments (EBTs) in community settings. The NIMH Strategic Plan states that one of the most important challenges of the next 20 years for the field of mental health is to implement effective treatments, developed in research settings, in the community (i.e., Strategy 4.1, 4.2, and 4.3). This K23 application capitalizes on a planned transformation of child mental healt services in the public sector in the City of Philadelphia. The applicant will embed herself as part of this natural experiment in community mental health clinics (CMHCs). Specific training goals for this 5-year-period, to be achieved under the mentorship of David Mandell, ScD, an expert in implementation science, and a team of expert consultants, are designed to engender applicant expertise in: (1) CMHC response to policy: understanding CMHC response to a system-level mandate of implementation of child EBTs in the public sector~ (2) organizational and leadership moderators: examining the impact of organizational- and leader-level factors on variability in EBT implementation~ and (3) intervention development: building expertise in the use of intervention mapping to lead to future implementation intervention development. The research component of this K23 includes three projects that build upon each other. The first project will use quantitative methods to answer the following question: To what extent do CMHCs (n = 30) implement child EBTs in response to a system-level policy mandate? The primary implementation outcome is fidelity at the individual provider level (n = 120) as measured by self-report and brief observation, three times over five years. One wave of data collection will occur prior to the initiation of the mandate. In project 2, the applicant will use quantitative methods to answr the following question: Do organizational- and leadership-level variables moderate implementation success? Organizational-level (i.e., organizational culture, organizational climate, implementation climate) and leader-level (i.e., knowledge of EBTs, leadership style, attitudes towards EBTs) predictors of implementation of child EBTs in CMHCs (N = 30) will be measured three times over 5 years. In project 3, beginning in the third year, the applicant wil study 6 CMHCs in depth using qualitative methods that are high- performing, average-performing, and low-performing to understand their experience around the implementation process using interviews. Findings from the proposed research will inform both future policy mandates around implementation and the support required for the success of these policies, increase the number of youth who can access quality psychosocial treatment, and reduce the research-practice gap.